Stimulus devaluation induced by stopping action.

Division of Humanities and Social Sciences and Computation and Neural Systems Program, California Institute of Technology.

Abstract

Impulsive behavior in humans partly relates to inappropriate overvaluation of reward-associated stimuli. Hence, it is desirable to develop methods of behavioral modification that can reduce stimulus value. Here, we tested whether one kind of behavioral modification--the rapid stopping of actions in the face of reward-associated stimuli--could lead to subsequent devaluation of those stimuli. We developed a novel paradigm with three consecutive phases: implicit reward learning, a stop-signal task, and an auction procedure. In the learning phase, we associated abstract shapes with different levels of reward. In the stop-signal phase, we paired half those shapes with occasional stop-signals, requiring the rapid stopping of an initiated motor response, while the other half of shapes was not paired with stop signals. In the auction phase, we assessed the subjective value of each shape via willingness-to-pay. In 2 experiments, we found that participants bid less for shapes that were paired with stop-signals compared to shapes that were not. This suggests that the requirement to try to rapidly stop a response decrements stimulus value. Two follow-on control experiments suggested that the result was specifically due to stopping action rather than aversiveness, effort, conflict, or salience associated with stop signals. This study makes a theoretical link between research on inhibitory control and value. It also provides a novel behavioral paradigm with carefully operationalized learning, treatment, and valuation phases. This framework lends itself to both behavioral modification procedures in clinical disorders and research on the neural underpinnings of stimulus devaluation.

Bidding data from the valuation phase in Experiments 1 and 2. Depicted are bidding levels from low bids (1) to high bids (6), plotted by the actual value of each shape from the learning phase (L = low, LM = low-medium, HM = high-medium, H = high). No stop and Stop refer to whether the shapes were paired stop-signals or not in the earlier treatment phase. Error bars denote the standard error of the mean across subjects.

Bidding data from the valuation phase in Experiments 3 and 4. Depicted are bidding levels from low bids (1) to high bids (6), plotted by the actual value of each shape from the learning phase (L = low, LM = low-medium, HM = high-medium, H = high). A) Congruent denotes trials that were paired with congruent Simon trials only (in the earlier treatment phase), incongruent denotes trials that were paired with incongruent Simon stimuli on 75% of trials. B) No-tone, single-response denotes trials that were always paired with the single-response requirement, Tone, double-response denotes trials that were paired with the double-response requirement 75% of the time. Error bars denote the standard error of the mean across subjects.